Human variability in multifactorial traits will be studied and analyzed with a view to determining how much of it is due to genetic influences, and where possible the mode of genetic action determined. New statistical techniques will be devised for this purpose, and applied both to data that have already been collected and to data that will be collected with the special purpose of identifying major genes for such traits. The possible existence of such major genes will be demonstrated by pedigree analysis, and by a search for linkage relationships between such genes and marker genes in blood. This will lead to a more complete understanding of the determinants involved in the development of the human phenotype. BIBLIOGRAPHIC REFERENCES: R.C. Elston. "Genetic methods for study of atherosclerosis", Report from the National Heart and Lung Institute Task Force on Genetic Factors in Atheroscleroic Disease, DHEW Publication No. (NIH) 76-922, April 1976, 223-229. R.C. Elston. "Tools of genetic analysis - Part II", Report from the National Heart and Lung Institute Task Force on Genetic Factors in Atherosclerotic Disease, DHEW Publications No. (NIH) 76-22, April 1976, 151-159.